Material application systems are regularly used for applying liquid coating material to an object, part or other work piece or surface. Material application systems typically include a material application device, also referred to as a spray gun or dispenser. A spray nozzle assembly may be mounted at a spray end of the spray gun and includes a nozzle tip having an orifice through which the liquid coating material is discharged, usually under pressure. Due to the wide variety of materials that can be applied, there is also a wide variety of spray nozzle assembly designs. A spray nozzle assembly is used generally to atomize and/or electrostatically charge the liquid coating material and to produce a desired spray pattern. The spray nozzle assembly typically includes the nozzle tip and a nozzle tip holder or adapter. The spray nozzle assembly may include other parts such as seals, for example. The spray nozzle assembly is often mounted on the spray end of the spray gun or dispenser using a retaining nut or other suitable arrangement.
Some work pieces, for example, single open ended cans, need a controlled or directional spray pattern to optimize application of material to the surfaces of interest. A controlled spray pattern is any spray pattern that is produced with a non-uniform distribution of material about the central longitudinal axis of the nozzle tip. Controlled spray patterns are needed in many applications in which it is desired to direct material in a particular manner at the surface being coated. One example of a controlled spray pattern is a directional spray pattern which is simply a spray pattern in which the material exits the nozzle tip in an asymmetrical pattern relative to the central axis of the nozzle tip. An asymmetrical pattern is a spray pattern that has a shape that is heavier on one side or skewed to one side with respect to the central axis of the nozzle tip. A controlled spray pattern may also be used in which the nozzle tip is offset at an angle from the central longitudinal flow axis through the spray gun and particularly nozzle adapter. Controlled and directional spray patterns and the nozzle designs to produce them are well known in the art. Further information as to asymmetric spray patterns and nozzles therefor can be found in U.S. Pat. No. 7,458,524 issued to Prieto, et al. for SPRAY NOZZLE WITH ALIGNMENT KEY, the entire disclosure of which is fully incorporated herein by reference.